1. Field
The following description relates to a method for producing 5-hydroxymethyl-2-furfural from maize syrup containing fructose, and more particularly, to a method for converting and purifying a raw material of maize syrup containing fructose that can be mass produced from carbohydrate biomass such as maize through a fermentation process, with an improved yield rate of 5-hydroxymethyl-2-furfural which is a core intermediate compound for biofuel and bioplastic, using a nonuniform solid acid catalyst having a dioxane solvent and an acid radical.
2. Description of Related Art
Oil demand is rapidly increasing due to the continuous decrease of oil reserves and growth of emerging & developing countries, causing imbalance of supply and demand in oil markets and leading to an era of high oil prices. Moreover, irreversible green house gases generated by reckless use of oil are causing serious environmental problems such as global warming.
Thus, the entire world is making efforts to replace oil resources with biomass resources that are replaceable and sustainable, for example, to mass produce commercial biofuels such as bioethanol and biodiesel, and bioplastic such as lactic acid and propanediol, to use them as transportation fuels and alternatives to petrochemicals.
As part of such efforts, 5-hydroxymethyl-2-furfural (HMF) which is a representative carbohydrate biomass-derived furan compound and a core intermediate compound for biofuel and bioplastic, is in the spotlight these days.
It is well known that 5-hydroxymethyl-2-furfural can be converted into 2,5-dimethylfuran (DMF) and 5-alkoxymethyl-2-furfural (AMF), and be used as the next generation biofuel. Furthermore, 5-hydroxymethyl-2-furfural has an energy density of gasoline level, and unlike bioethanols, it has a low hygroscopicity, thus there is no problem of corrosion even when stored for a long time. Not only that, unlike when producing bioethanol through an enzyme conversion process where 2 equivalents of carbon dioxide are inevitably discharged from 1 equivalent of hexose (C6H10O6→2CH3CH2OH+2CO2⇑), the furan biofuels can be produced through a complete carbon-neutral process where there is no loss of carbon.
Furthermore, 5-hydroxymethyl-2-furfural can be converted into 2,5-furan dicarboxylic acid (FDCA), which is well known as an alternative to terephthalic acid (TPA), a monomer of PET. PET is produced through condensation polymerization using ethylene glycol (EG) and TPA as monomers, but while EG is under commercial production from bioethanol-based bioethylene to produce biomass-based PET, TPA is not being obtained from biomass yet.
Meanwhile, maize syrup containing fructose refers to high fructose maize syrup (HFCS), that has been under mass production since its manufacturing technology was first developed by Marshall in 1957 (R. O. Marshall, E. R. Kooi, Science, 1957, 125, 648), and is being widely used in food and beverage industries as an alternative to sugar. Maize syrup containing fructose is a mixture compound containing a large amount of fructose produced by converting maize that is a type of carbohydrate biomass, through a fermentation process. Furthermore, depending on the composition of fructose, HFCS may be classified into HFCS-90, HFCS-55, and HFCS-42 type HFCS that contains 90 parts by weight, 55 parts by weight, and 42 parts by weight, respectively. HFCS contains water and thus has a form of syrup.
Fructose which is the main substance of maize syrup containing fructose is well known to be converted into 5-hydroxymethyl-2-furfural when 3 water molecules are removed through a dehydration reaction. Recently, 5-hydroxymethyl-2-furfural is used as a core intermediate compound for biofuel and bioplastic, and so a lot of researches are being conducted for ways to mass produce 5-hydroxymethyl-2-furfural, but processes for commercially producing 5-hydroxymethyl-2-furfural have yet to be developed.
Most of the methods for converting fructose into 5-hydroxymethyl-2-furfural developed so far use dimethyl sulfoxide (DMSO) as solvent. That is because, by heating fructose under an acid condition, for 1 to 2 hours at 80 to 150° C. using DMSO as solvent, as much as 70 to 90% of the fructose can be converted into 5-hydroxymethyl-2-furfural. However, the boiling point of DMSO is very high, 189° C., and thus it is difficult to isolate DMSO through distillation. Not only that, DMSO can easily mix with most of other solvents, and thus there is also a disadvantage that it is difficult to recover 5-hydroxymethyl-2-furfural from DMSO through solvent extraction.
In order to solve the aforementioned problems, attempts have been made using DMSO with other solvents to conduct a conversion reaction in a binary system, in order to extract in real time the reactant product, 5-hydroxymethyl-2-furfural (G. W. Huber, J. N. Chheda, C. J. Barrett, J. A. Dumesic, Science 2005, 308, 1446), but there were limitations in extracting HMF completely from DMSO.
Therefore, to replace DMSO, DMF (N,N-dimethylformamide) which has a lower boiling point (G. A. Halliday, R. J. Young, V. V. Grushin, Org. Lett. 2003, 5, 2003) or ionic liquids from which a reactant product can be extracted easily (H. B. Zhao, J. E. Holladay, H. Brown, Z. C. Zhang, Science, 2007, 316, 1597) were used. However, the boiling point of DMF is still high (153° C.), and so are the prices of ionic liquids, and thus they are not economically feasible to be applied to commercial mass production.